1. Field of the Invention
The present invention relates to connection devices in vehicle seats. More particularly, the present invention relates to connection devices for rotatably connecting two components (e.g., seat backs and seat cushions) of vehicle seats.
2. Description of Related Art
Generally, a vehicle seat includes a seat back and a seat cushion. The seat back and the seat cushion are rotatably connected via a seat reclining device for adjusting a tilt angle of the seat back. Such a seat reclining device is taught, for example, by Japanese Laid-Open Patent Publication Number 2007-130237.
The known seat reclining device includes a pair of opposing disk-shaped housings, i.e., a first or rotational housing (ratchet) and a second or stationary housing (guide). The first housing is affixed to the seat back. The second housing is affixed to the seat cushion. The first and second housings are axially mated or coupled to each other, so as to move or rotate relative to each other around a rotational shaft. Also, the first and second housings are circumferentially connected by an annular fastener or clip ring along peripheral edges thereof, so as to not be axially disengaged from each other.
The seat reclining device further includes a locking mechanism that can prevent the first housing from rotating relative to the second housing, so as to lock the seat reclining device. The locking mechanism essentially consists of a slide cam and slide pawls that are positioned between the housings. The slide cam is slidably received between guide members that are formed within the second housing, so as to radially move on the second housing when the rotational shaft is rotated. Conversely, the slide pawls are slidably received between the guide members, so as to radially move on the second housing. Further, the slide pawls are respectively arranged so as to move in the directions perpendicular to the slide cam. In addition, each of the slide pawls is provided with a convex toothed portion.
When the rotational shaft is rotated to a locking position, the pawls are radially moved outward via the slide cam, so that the respective convex toothed portions of the pawls engage a concave toothed portion that is circumferentially formed over an inner circular surface of a peripheral edge of the first housing. In this state, the first housing is prevented from rotating relative to the second housing, so that the seat reclining device is locked. As a result, the seat back is locked in position relative to the seat cushion.
In the seat reclining device, the second housing (guide) is constructed to receive the first housing (ratchet) therein. That is, the first and second housings are respectively constructed such that a peripheral edges of the second housing can circumferentially encircle a peripheral edge of the first housing when they are mated or coupled to each other.
In order to assemble the seat reclining device using a manufacturing machine, the slide cam and the slide pawls are attached to the second housing (guide). Thereafter, the first housing (ratchet) is placed on the second housing, so that the first and second housings are mated or coupled to each other. At this time, the peripheral edge of the first housing can be encircled by the peripheral edge of the second housing. Subsequently, the clip ring is placed on the first housing. In particular, the clip ring is a shouldered annular steel ring and has a first annular retainer portion (a first annular support wall), a second enlarged annular retainer portion (a second annular support wall) and a foldable annular periphery (a fixing portion). Therefore, the clip ring is placed on the first housing such that the first and second annular retainer portions of the clip ring respectively contact an outer annular surface of the peripheral edge of the first housing and an inner annular surface of the peripheral edge of the second housing. Finally, a peripheral edge of the foldable annular periphery of the clip ring thus positioned is circumferentially bent onto an outer annular surface of the peripheral edge of the second housing by crimping. Thus, the clip ring is fixed to the peripheral edge of the second housing while the peripheral edge of the first housing is held by the first annular retainer portion thereof, so that the first and second housings can be circumferentially fastened or clamped to each other.
Generally, the peripheral edge of the foldable annular periphery of the clip ring is bent onto the outer annular surface of the peripheral edge of the second housing by crimping while the second annular retainer portion of the clip ring is circumferentially supported by a support member (a support die). That is, the second annular retainer portion of the clip ring is utilized as a support surface supported by the support member when the clip ring is crimped. However, the clip ring may generally be formed by circumferentially bending a cylindrical steel ring, so as to have the first and second annular retainer portions. Therefore, an annular curved bent portion can be inherently formed between the second annular retainer portion and the foldable annular periphery. As a result, the second annular retainer portion of the clip ring has a reduced area. That is, an area of the support surface (the second annular retainer portion) supported by the support member is narrowed or reduced. This means that the second annular retainer portion of the clip ring cannot be sufficiently supported by the support member when the clip ring is crimped. This may lead to reduced accuracy of bending (crimping).